The elucidation of the chemical structures the gonadotropins has posed may question concerning the mechanism of their biosynthesis. The objective of this proposal will be to establish tools (purified mRNAs) with which to study the biosynthesis of the gonadotropins in the rat pituitary. The specific aims and approaches include: 1) To determine the effects of of orchidectomy, and orchidectomy plus chemical thyroidectomy on pituitary gonadotropin production and secretion as evaluated by (a) cytological examination (b) tissue and sera hormone concentrations (RIA) and (c) identification and quantification of cell-free products translated by total pituitary polysomes using amino acid incorporation and radioimmunoassay; 2) To prepare polysomes responsible for alpha subunit synthesis by immunoprecipitation with specific antisera and isolate poly A RNA by phenol extraction and oligo (dT) cellulose chromatography; 3) To identify the products synthesized in various cell-free systems in response to this purified mRNA by immunoprecipitation, electrophoresis and enzymatic peptide mapping; 4) To purify and characterize the alpha subunit mRNA by sucrose gradient density centrifugation, formamide and agarose gel electrophoresis and cell-free product identification; and 5) To separate, purify and characterize the gonadotropin beta subunit mRNAs. The availability of purified gonadotropin subunit mRNAs would provide new information regarding gonadotropin biosynthesis and would facilitate future studies in the investigation of the regulatory mechanisms involved in the expression of the genes coding for these hormones.